Publication: Line-strength indices in bright spheroidal galaxies: Evidence for a stellar population dichotomy between spheroidal and elliptical galaxies
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1997-05-20
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Pedraz, Santos
Guzmán, Rafael
González, J. J.
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IOP Publishing
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Abstract
We present new measurements of central line-strength indices (namely, Mg-2, (Fe), and H beta) and gradients for a sample of six bright spheroidal (Sph) galaxies in the Virgo Cluster. Comparison with similar measurements for elliptical (E) galaxies, galactic globular clusters (GGCs), and stellar population models yield the following results: (1) in contrast with bright E galaxies, bright Sph galaxies are consistent with solar abundance [Mg/Fe] ratios; (2) bright Sph galaxies exhibit metallicities ranging from values typical for metal-rich GGCs to those for E galaxies; (3) although absolute mean ages are quite model dependent, we find evidence that the stellar populations of some (if not all) Sph galaxies look significantly younger than GCCs; and (4) Mg-2 gradients of bright Sph galaxies are significantly shallower than those of E galaxies. We conclude that the dichotomy found in the structural properties of Sph and E galaxies is also observed in their stellar populations. A tentative interpretation in terms of differences in star formation histories is suggested.
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© 1997. The American Astronomical Society. All rights reserved. We are grateful to the anonymous referee, A. Aragón Salamanca, J. Gallego, and R. Peletier for useful comments. The INT is operated on the island of La Palma by the RGO at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This work was supported in part by the Spanish grant PB93-456. R. G. acknowledges funding from the Spanish MEC fellowship EX93-27295297 and NSF grant AST91-20005.
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Babul, A., & Rees, M. 1992, MNRAS, 255, 346
Bender, R. 1991, in IAU Symp. 149, The Stellar Populations of Galaxies, ed. B. Barbuy & A. Renzini (Dordrecht: Kluwer), 269
Bender, R., Burstein, D., & Faber, S. M. 1992, ApJ, 399, 462
Binggeli, B. 1994, in ESO Conf. and Workshop Proc. 49, Dwarf Galaxies, ed. G. Meylan & P. Prugniel (Haute Provence: ESO), 13
Binggeli, B., & Cameron, L. M. 1991, A&A, 252, 27
Binggeli, B., Sandage, A., & Tammann, G. A. 1985, AJ, 90, 1681
Bothun, G. D., & Mould, J. R. 1988, ApJ, 324, 123
Brodie, J. P., & Huchra, J. P. 1991, ApJ, 379, 157
Burstein, D., Faber, S. M., Gaskell, C. M., & Krumm, N. 1984, ApJ, 287, 586
Caldwell, N. 1983, AJ, 88, 804
Chaboyer, B. 1994, in ESO Conf. and Workshop Proc. 49, Dwarf Galaxies, ed. G. Meylan & P. Prugniel (Haute Provence: ESO), 485
Covino, S., Galletti, S., & Pasinetti, L. E. 1995, A&A, 303, 79
da Costa, G. S. 1991, in IAU Symp. 149, The Stellar Populations of Galaxies, ed. B. Barbuy & A. Renzini (Dordrecht: Kluwer), 191
Davies, R. L., Sadler, E. M., & Peletier, R. F. 1993, MNRAS, 262, 650 (DSP)
Dekel, A., & Silk, J. 1986, ApJ, 303, 39
Ferguson, H. C. 1994, in ESO Conf. and Workshop Proc. 49, Dwarf Galaxies, ed. G. Meylan & P. Prugniel (Haute Provence: ESO), 475
Ferguson, H. C., & Binggeli, B. 1994, A&A Rev., 6, 67
Fisher, D., Franx, M., & Illingworth, G. 1995, ApJ, 448, 119
González, J. J. 1993, Ph.D. thesis, Univ. of California, Santa Cruz (G93)
González, J. J., & Gorgas, J. 1997, in preparation
Gorgas, J., Efstathiou, G., & Aragón Salamanca, A. 1990, MNRAS, 245, 217
Gorgas, J., Faber, S. M., Burstein, D., González, J. J., Courteau, S., & Prosser, C. 1993, ApJS, 86, 153 Gorgas, J., Pedraz, S., Guzmán, R., González, J. J., & Cardiel, N. 1997, in preparation
Gregg, M. D. 1991, in IAU Symp. 149, The Stellar Populations of Galaxies, ed. B. Barbuy & A. Renzini (Dordrecht: Kluwer), 426
Guzmán, R., Lucey, J. R., & Bower, R. G. 1993, MNRAS, 265, 731
Held, E. V., & Mould, J. R. 1994, AJ, 107, 1307
Kormendy, J. 1985, ApJ, 295, 73
Kormendy, J., & Bender, R. 1994, in ESO Conf. and Workshop Proc. 49, Dwarf Galaxies, ed. G. Meylan & P. Prugniel (Haute Provence: ESO), 161
Peletier, R. F. 1989, Ph.D. thesis, Rijksuniversiteit Groningen
Salpeter, E. E. 1955, ApJ, 121, 161
Vader, J. P., Vigroux, L., Lachièze-Rey, M., & Souviron, J. 1988, A&A, 203, 217
Vazdekis, A., Casuso, E., Peletier, R. F., & Beckman, J. E. 1996, ApJS, 106, 307
Worthey, G. 1994, ApJS, 95, 107
Worthey, G., Faber, S. M., & Gonza´lez, J. J. 1992, ApJ, 398, 69